Limit-switch device.



PATENTED JUNE 23, 1908.

S. H. KANMAGHER. LIMIT SWITCH DEVICE. APPLICATION FILED DEO.18.1905.

Witnesses:

Inve rater UNITED STATES r trEN'roEEIo SAM H. KANMACHEE,

OF SCHENECTADY,'NEW YORK, AssIeNoE TO GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

LIMIT-SWITCH DI E VICE.

To all whom it may concern:

Be it known that I, SAM H. KANMAcHER,

a citizen of the United States, residing at Schenectady, county of Schenectady, and State of New. York, have invented certain new and useful Improvements in Limit- Switch Devices, of which the following is a specification.

The present invention relates to control apparatus for electric motors and more particularly to means for bringing a motor to rest after it has made a predetermined number of revolutions in one direction or in either direction; and the present invention has for its ob ect a novel construction and arrange-' ment of parts to be hereinafter described and particularly pointed out in the claims.

In the accompanying drawing, Figure 1 indicates diagrammatically a preferred form of the present invention; and Fig. 2 a'detail showing the manner of operating the limit switches at the extreme limits of movement of a member which is adapted to be reciproand to control the speed of the motor when starting.

0 is a relay adapted to control the. motor circuit either directly, as shown, or indirectly; the object of this relay being to cause the motor circuit to be interrupted and the motor brought to rest when the motor has made a prescribed number of revolutions or the member adaptedt be moved by the motor has reached its extreme limit. The relay is illustrated as having three coils, 0

0 and 0 these coils being so proportioned thatwhen two of them are energized so as to have like polarities they. serve to lift the movable member 0 of the relay; while if two of the coils are energized so as to have op 0- site polarities they neutralize each 'ot er either wholly or to such an extent that their cumulative effect is insuflicient to either lift or maintain the movable element of the relay. The coil 0 is connected through the con- Specification of Letters Patent. Application filed December is, 1905. Serial No. 292,181.

Patented June as, 1908.

troller to the line, so that when the controller is moved into either its forward or reverse running position this Coil is energized by current flowing through it in a constant direc tion. The coils 0 and 0 respectively, are so connected that they are maintained at opposite polarities and their polarities are reversed when the controller is moved from either forward or reverse to the op osite position. The circuit containing 001 o is only completed when limit switch S is closed, and the circuit for the coil 0 is similarly completed through limit switch S Assuming that the controller has been moved to the left into the position wherein the movable contacts engage with the fixed contacts along line 1, 1 and that the relay has been actuated, a circuit may be traced from line L, through contacts Z, k, 7c, 1, throu h resistance R, field winding f, contacts 1 k Z through the contacts 0 of the relay,

through the motor armature, contacts 1 742k and l to line L. A branch circuit may be traced from the right'hand terminal of the field Winding, through the coil 0 of the relay, directlyback to line L, thus energizing coil 0 sufficiently to maintain the relay in its closed position. Other branch circuits lead from the same terminal of the field winding, namely from the lead. between contact 1 and the Contact 0 of" the relay, through the coils 0 and o of the-relay and thence through switches S and 8*, respectively, contacts k 7c, I back to line L. The coils 0 and 0 are wound in opposite directions so that if both ofthe limit switches S and S are closed the effect of these coils will be to neutralize each other; while if only switch S is closed the coil 0 will assist the coil 0 and if switch S alone is closed, the coil 0 will oppose the coil 0 Thus it will be seen that if, before the controller is moved to its operative position,

the switch Sis closed and the switch S3 is left open, both coils 0 and 0 will be energized when the controller is moved into the position, assumed, thereby causing the relay to operate to complete the motor circuit. If

now switch S is opened, the relay will be i I maintained inits actuated position by the coil 0 If the switch S is closed, the coil 0 will be energized, and, since its effect is to oppose the coil 0 the core'of the relay will dro and the motor circuit be opened. If,

whi' e the switch-S remains closed, the controller is moved into the reverse running pcthe coilo in the opposite direction from that direction suc in which it reviously flowed, namely, in a $1 that the coil 0 assists the coil 0 to o erate the relay. If now switch S is opene and switch S closed, coil 0 is deenergized andcoil 0 energized, but this latter coil instead of assisting the coil 0 as before now olprposes it, since the direction of current flow t ough it has been reversed, and therefore the core of the relay drops and the motor circuit is opened. It is seen that in this reverse positlon of the controller the current through the armature, which is connected in parallel with the coils 0 and 0 is reversed so that the direction of rotation of themotor is the reverse of that which takes place when the controller is in its forward running position.

I have made use of switches S and S for automatically stopping the motor after it has made a in one irection or the other. the switches S and S may be spring-actuated so as to remain normally open and they may be alternately closed through engagement with projections 25 and t on a table or other member T which is adapted to be reci rocated between defined limits by means 0 the motor M. The motor is illustrated as geared to the table by means of gearing P and a rack P InFig. 2 the table is illustrated in one of its extreme ositions, namely, that position wherein switc S is closed. It is evident if now the controller is moved to the left the relay will be actuated and the motor started. The direction of rotation of the motor is such as to move the table toward the right, and, as the table begins its travel, the switch S is released and o ens;

the relay, however, is maintained 0 osed malntaining coil 0 vvuntil the table reaches its other extreme through the action of O- sition wherein it closes switch S is causes the coil 0 to be energized, but in a manner that it opposes the action of coil 0 and the relay drops and opens the motor cirout, bringing the motor and table to rest. When it is desired to move the table back to its original position, the controller is-reversed and the relay is actuated in the manner previously described, through coils 0 and 0. The motor circuit is now complete and the motor operates until the table reaches the position shown and causes the coil 0 to be redetermined number of revolutions For example,

such

energized so as to oppose the coil 0 thereby letting the relay drop and open the circuit.

In the second and third running positions 'of the controller for either direction of rotation of the motor, half and then all of the resistance R is cut out so that the motor, is finally connected directly across the line i11- dependently of the resistance. It is evident that this method of controlling the speed of the motor forms no part of the present invention and may be varied as may also the type of motor and the manner in which the relay controls the motor circuit. If the coils of the relay are so proportioned that one alone is insu'llicient to raise the core of the relay, while am le to maintain it raised, then if the current rails or the controller is turned off while the table or other member is in an intermediate position, it will be impossible to start it again unless the relay is closed manually or one of the limit switches is momentarily closed. On the other hand, if one of the coils alone is suliicient to lift the relay core then the motor circuit may be completed at any time upon operating the control er in the proper or desired direction. The condition of service will, of course, determlne wh ch of the two arrangements will be used.

What 'I claim as new and desire to secure by Letters Patent of the United States, is, 1. In combination, a motor, a reversing controller, a relay for controlling the circuitof said'motor, actuating coils on said relay, connections between controller and said coils arranged to change the relative polaritiesof sai coils in the forward and reverse positions of the controller, a switch in the circuit containing one of said coils, and means controlled by said motor for operating said switch.

2. In combination, a motor, a reversing controller, a relay for controlling the circuit of said motor, two actuating coils on said relay, connections between said actuating coils and said controller arranged to cause said coils to operate cumulatively in the forward running position of the controller and to oppose each other in the reverse position of the controller, a switch in the circuit including one of said coils, and a devicegeared to the motor for controlling said switch.

3. In combination, a motor, a member geared to said motor and adapted to be moved thereby between predetermined limits, a relay for controlling the circuit of said motor and having two positions, means controlled by said controller and said member when said member is in one of its extreme positions for causing said relay to assume one of its said positions when the controller is in one running position and the other of its said positions when the controller is in the opposite running position.

4. In combination, a motor, a member geared to said motor and adapted to be moved within predetermined limits, a reversing controller, a relay for controlling the circuit of said motor, means controlled by'said controller and said member for causing said relay to operate to complete the motor circuit 7 when the controller is in one of its running positions and the said member is in its-extreme position corres onding to the reverse position of the contro ler and for causing said relay to operate to open the motor circuit when the said member has moved to its other extreme position.

5. In combination, a motor, a reversing controller, a relay for controlling the circuit ol said motor, two actuating coils on said relay, connections between said actuating coils and said controller arranged to cause said coils to act cumulatively in one position of the controller and to oppose each other in the reverse. position of the controller, a norn-ially open. switch in the circuit containing one of said coils, and member operated by said motor for closing said switch.

(5. In combination, a motor, a reversing controller, a relay for controlling the circuit of said motor, a maintaining coil and two auxiliar' coils on said relay, connections between saidcoils and said controller arranged to maintain said auxiliary coils at opposite polarities and to reverse the polarities of said auxiliary coils upon reversal of the controller, switches in the circuits containing said auxiliary coils, and means controlled by said motor for operating said switches.

7. In combination, a motor, a reversing controller, a relay for controlling the circuit of said motor, a maintainingcoil and a pair of auxiliary coils on said relay, connections between said coils and said controller arranged to maintain said auxiliary coils at opposite polarities and to reverse the polarities of said auxiliary coils upon reversal of the controller, a member adapted to be operated by said motor between defined limits,

a switch in the circuit containing one of said auxiliary coils arranged to be operated by said member 1n one of its extreme positlons,

' and a second switch in the circuitof the other auxiliary coil arranged to be operated by said member when in its other extreme position.

In Witness whereof; I have hereunto set my hand this 15th day of December, 1905. SAM Hj KANMACHER.

Witnesses:

' BENJAMIN B. HULL, f

HELEN ORFORD. I 

